ZIEGLER –NATTA AND STEREOCHEMICAL CONTROL IN POLYMERIZATION Anand S. Burange, Wilson College, Mumbai asgburange@gmail.com Introduction The traditional route for the synthesis of LDPE (Low Density Polyethylene) requires very high pressure i.e. nearly 20,000 psi and high temperatur e (500 o C). These stringent reaction conditions have safety issues. But these severe conditions can be overcome by Ziegler-Natta catalyst where polymerization takes place at comparatively lower reaction temperature and pressure . The catalyst is also useful to synthesize HDPE which is composed of long linear chain that pack closely together to form rigid polymer. There are various Ziegler-Natta catalysts reported so far. The most commonly used, is the combination of TiCl 4 and triethylaluminium (Et 3 Al). The catalyst must be handled with care because it catches fire on contact with air. Before 1953, isotactic and syndiotactic addition polymers were unknown. Karl Ziegler, Germany and Giu